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From solmyr72 <>
Subject Losing messages (asyncSend, but slow message rate)?
Date Thu, 03 Jul 2008 13:19:47 GMT


While running our tests, we noticed that ActiveMQ loses some messages.
We use 'asyncSend', so we realize it's possible to lose messages. 
Still, we were a bit surprised given the relaxed conditions of the test:
it's only 60 short messages, using TCP transport, on a stable network.

Our test is as follows:

0) We're using:
- ActiveMQ 4.1.1, with asynchSend, and TCP transport
- Our JMS sessions are NOT transacted
- Windows XP, SP2
- CUP: about 3MHz , memory: 2GB

1) We have one process called 'client', and one 'server'.
- The client sends a request message to the server ("how are you"). Before
sending, it subscribes a listener for the expected reply (based on
- The server subscribes a single listener, which replies to incoming
requests ("I'm fine, thanks").

2) Our client sends 30 such requests, yielding 30 replies (total: 60
They are sent almost "all at once", but it's only a single peak (the whole
test takes mere seconds).

3) Messages are short ("how are you")

4) Broker & clients are all on the same computer (strong XP machine).
So it's TCP on loopback - theres is no reason to lose any data, is there ?

We ran this test several times. 
Sometimes we'd lose no messages; but sometimes we'd lose  1-3 messages (out
of 60).
Could anyone please explain what might cause this?

Thanks very much:

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